Convolute wound fibre drum with thermoplastic adhesive

ABSTRACT

A convolute wound fibre drum comprising several plies of convolutely wound container board for forming a tubular member, the plies being adhesively secured to one another by a layer of thermoplastic material. The tubular member has a metal chime attached at each end by an indentation of a portion of said chime and said tubular member. The thermoplastic material between the plies and adjacent said indentations has a greater elasticity than the thermoplastic intermediate said indentations so as to preclude the rupture of the fibres upon forming said indentation.

United States Patent 1 1 Szatkowski 1 June 24, 1975 [54] CONVOLUTE WOUND FIBRE DRUM WITH 3.242.829 3/1966 1/1616 253/45);

3,555,976 1/1971 arter et a 4 R THERMOPLASTIC ADHESIVE 3.656.513 4/1972 Evans et a1. 229/45 x Richard R. Szatkowski, Western Springs, 111.

[75] Inventor:

Assignee: Continental Can Company. lnc.,

New York, NY.

Filed: Nov. 24, 1972 Appl. No: 309,561

References Cited UNITED STATES PATENTS 4/194l Bronson 229/56 X 7/1956 Stahl 1 1 .1 93/94 R X l/l965 Freese 93/94 R Primary Examiner-William 1. Price Assistant E.wminerStephen P. Garbo Attorney, Agent, or FirmDi1ler, Brown, Ramik & Wight [57] ABSTRACT A convolute wound fibre drum comprising several plies of convolutely wound container board for forming a tubular member, the plies being adhesively secured to one another by a layer of thermoplastic material. The tubular member has a metal chime attached at each end by an indentation of a portion of said chime and said tubular member. The thermoplastic material between the plies and adjacent said indentations has a greater elasticity than the thermoplastic intermediate said indentations so as to preclude the rupture of the fibres upon forming said indentation.

5 Claims, 6 Drawing Figures PATENTEDJUN 24 I975 mm hm CONVOLUTE WOUND FIBRE DRUM WITH THERMOPLASTIC ADHESIVE BACKGROUND OF THE INVENTION This invention relates to containers formed of convolutely wound paperboard. More specifically, it relates to a convolutely wound tubular member having a thermoplastic adhering several plies of paperboard together and chimes at each end for securing a closure thereto.

Fibre drums are conventionally manufactured by convolutely winding paperboard about a mandrel while applying a water base or hot melt adhesive to one side of the paperboard to bind the plies of the paper one to another. The resulting tubular member has substantial stacking strength and is suited for use as a container which is completed by crimping a metal chime to the upper and lower end for securing closures thereto. However, the crimping operation requires a pliable tubular member. but such can not be readily obtained when conventional adhesives are utilized. For these reasons, the manufacturer of such drums in the prior art has sprayed water or wetting agents on the paperboard as it was wound about the mandrel so as to permit the desired distortion of the paper in the chime areas without rupture of the paper plies. However. such wetting also reduces the vertical stacking strength of the container, and requires that such drums, after manufacture, be stored so as to permit the wetted portion to dry. Obviously. such causes substantial inventory problems.

SUMMARY OF THE INVENTION In order to obtain a convolute wound fibre drum which omits the wetting requirement of the prior art manufacture, the instant invention relates to a convolute wound drum having a thermoplastic adhesive between the plies of paperboard. Additionally, the thermoplastic is either selected or placed upon a board in such a manner as to provide substantial rigidity over a major portion of the drum and yet provide greater elasticity at the ends thereof so as to permit deformation of the wound tubular member without rupture of the paperboard.

Accordingly, it is an object of the instant invention to provide an improved fibre drum utilizing convolute wound, thermoplastic coated container board. Too, it is an object of the instant invention to provide a convolute wound tubular member which will provide enhanced stacking strength as well as sufficient flexibility to permit crimping and deformation of the tubular member without rupture of the fibres upon attachment of the metal chimes thereto. Finally, it is an object of the instant invention to provide a process for the manufacture of convolute wound fibre drums which avoids the necessity for wetting the fibre of container board prior to the crimping and attachment of the metal chimes, and to additionally eliminate the need for a drying out period.

DESCRIPTION OF THE DRAWINGS The manner in which the objects of the instant invention is attained will be made clear by a consideration of the following specification and claims when taken in conjunction with the drawings in which:

FIG. 1 is a perspective view of a convolute wound fibre drum;

FIG. 2 is a side elevation view in section of a preferred embodiment of my invention prior to attachment of the metal chimes and end closures.

FIG. 3 is an enlarged view of a portion of FIG. 2;

FIG. 4 is a side elevation view in section illustrating the complete embodiment of FIG. 2;

FIG. 5 is a side elevation view in section of a thermoplastic coated paperboard used in the manufacture of my invention; and

FIG. 6 is a side elevation view in section of another thermoplastic coated board which may be used in the manufacture of my invention.

DETAIL DESCRIPTION As depicted in FIG. I, the conventional appearance of the fibre drum 10 takes the shape of an upstanding tubular member I2 formed of several plies of convolutely wound paperboard. At each end of this tubular member 12 is attached a metal chime 20 and 30, both of which may be adhesively secured to thc paperboard as well as mechanically interlocked thereto by indentations 24 and 38 and curls 22 and 36 as more thoroughly shown in FIG. 4.

The manufacture of such drums utilizes a convolute wound tubular member 12 having an upstanding side wall of several plies of paperboard as illustrated in FIGS. 2 and 3. These tubular members are conventionally formed by winding the board about a mandrel with a hot melt adhesive being applied to one side of the board during winding so as to effect adhesion between the plies. After this member is formed, a lower metal chime having a cylindrical side wall 32 and a bottom curl 34 is placed over the lower end while a closure member 40 having a depending annular flange 44 is placed inside member I2 adjacent the end. The upper chime 20 initially takes a form similar to that of the lower chime 30 as depicted in FIG. 2.

After the tubular member I2 and bottom 40 is forced downwardly into the curl 34, the metal chime and tubular member I2 is subsequently formed by completion of the curl as depicted in FIG. 4, and by a deformation or indentation of both the tubular member 12 and the metal chime 30 as shown in FIG. 4.

In the prior art manufacture, such a large deformation of the paper plies which results from the crimping action to form the groove 38, and the curling action to complete the curl 36 often rupture or fracture the paperboard thus resulting in poor containers. In order to overcome this problem, the prior art has utilized a wetting agent to wet the varies plies of paper as they are wound about a mandrel so as to provide more flexibility to the tubular member [2 in the vicinity of the chimes 20 and 30. However, such wetting reduces the vertical stacking strength of the container and requires a stor age time for the finished containers to permit the paper to dry out.

In order to overcome this problem, the preferred embodiment of my invention utilizes paperboard having a thermoplastic adhesive previously extruded or placed thereon by other means. In making the tubular member 12, the coated board is unwound across a table and cut into the length required to form the member I2 with the desired number of plies. and then is wrapped about a mandrel. During this wrapping or winding process, heat is applied to the thermoplastic to render it tacky, and upon cooling, adhesion between the plies results. A thermoplastic such polyethylene has a greater ad hesive strength between two plies of paper when it is extruded or placed upon the paperboard in a very thin layer. but of a sufficient thickness to insure complete coverage of the entire width of the board. Such improves stacking strength, but does not eliminate the problem of permitting deformation of the formed tubular member without rupturing of the container board itself.

To overcome this latter problem. my invention utilizes a paperboard coated with a polymeric material which has sufficient elasticity to accept deformation without rupture of the paperboard or the thermoplas tic.

As shown in FIGS. 5 and 6, the thermoplastic mate rial 54 adjacent each side of the paperboard 50 is formed or constituted to provide greater elasticity so as to absorb the forces causing deformation without transmitting them to the board. In FIG. 5, the greater elasticity is obtained by increasing the thickness of the thermoplastic material at 54 which ultimately forms the top and bottom end areas of the tubular member 12. Thus a thin layer 56 of thermoplastic material is placed upon the container board in the intermediate areas. while an increased thickness is placed at 54 upon which the metal chimes are placed and crimped. This greater thickness which is indicated at 54 will accept greater shearing forces in the crimping process without rupturing the thin film and subsequently permitting seepage of water through the side walls of the container. Preferably. it has been found that the intermediate area 56 of the paperboard between the metal chimes should have a thickness no greater than 0.5 mils. while the thermoplastic material at the ends of the tubular member 12 should have a thickness greater than 0.5 mils.

In the alternative embodiment of FIG. 6, protection against rupture of the fibre material upon crimping is effected by the selection of different thermoplastic adhesives. For example. the thermoplastic adhesive in the intermediate area 56 may be a low density polyethylene having a low percent elongation. while the thermoplastic adhesive in the areas 57 adjacent the end portions of the tubular member 12 or sheet of paper may comprise a polyethylene formulation having a greater percent elongation. Alternatively, a different thermoplastic might be utilized such as ethylene-vinyl acetate copolymers sold under the trademark Alathon by E.l. du Pont de Nemours. some of said copolymers having a percent elongation two or three times that of many low density polyethylenes.

The thermoplastic adhesives may be placed on the container board by conventional extrusion methods. or in the alternative. one can utilize electrostatic deposition of the powder on the paper with subsequent flame treatment to adhere the same thereto. Obviously, separate extruders or separate application of the electro static charged powder may be necessary.

As previously explained, the thermoplastic coated paperboard 50 of FIG. 5 or 6 is wound about a mandrel. and may be heated during winding so to render the thermoplastic adhesive tacky to obtain the adhesion between the several plies. FIG. 2 and the enlargement thereof in FIG. 3 depict the utilization of the coated board of FIGv 5, and illustrates the increased wall thickness of the tubular member at the lower end thereof; with the normal thickness in the intermediate area portion of tubular member 12. After the tubular member 12 is formed, and cooled. such that the thermoplastic material adhesivcly secures the paper plies one to another. the chime member 30, and the bottom closure 40 are placed on the lower end of the container. with an upper chime 20 being placed on the upper end. Subsequently. conventional methods are utilized to mechanically curl the chimes 22 and 36 as indicated in FIG. 4. and to deform the side wall of the metal chime and the container board to form the annular grooves 24 and 38 as indicated.

Due to the greater elasticity of the thermoplastic material adjacent the ends of the tubular member [2, such deformation permits formation ofthe curls and grooves without rupturing the thermoplastic film. or of the paper fibre of the container board. Obviously. such eliminates the prior need for the utilization ofa wetting agent to permit such deformation. and precludes the necessity for storage and drying of the formed container.

Within the scope of my invention is any tubular member which utilizes a thermoplastic adhesive for securing the convolute wound plies of paper together. and in which the elasticity of the material adjacent those areas which are to be deformed is greater than the elasticity of the thermoplastic material in the intermediate up standing side walls 12 of the container I0.

I claim:

1. In a fibre drum container having a tubular body member and a closure attached to at least one end by deformation of the tubular body member, the improvement comprising:

a. several plies of convolutcly wound paperboard;

and

b. a layer of thermoplastic adhering the plies of paperboard to one another, means for permitting deformation of the body member adjacent said one end without rupture of the paperboard, said means including said thermoplastic adjacent the deformed end having a greater elasticity than the remaining thermoplastic.

2. An article as recited in claim 1 in which said greater elasticity is obtained by:

a. increased thickness of the thermoplastic layer adjacent the deformed end as compared to other of said thermoplastic layer.

3. An article as recited in claim 1 in which:

a. the thickness of the layer of thermoplastic is uniform; and

b. the thermoplastic adjacent the deformed end has a greater percentage elongation prior to rupture.

4. A convolute wound fibre drum comprising:

a. several plies of convolutcly wound container board for forming a tubular member, said plies being adhesively secured one to another by a layer of thermoplastic material;

b. a metal chime at each end of said tubular member for securing a closure thereto. said chime being at tached to said tubular member by indentation of a portion of said chime and said tubular member; and

c. said layer of thermoplastic material being said plies and intermediate the indentations having a maxi mum thickness of 0.5 mils, and a thickness greater than 0.5 mils at said indentation for providing elasticity to the tubular member to preclude rupture of the fibre thereof.

5. A container comprising:

of the side walls. said chimes being secured to the tubular member by an annular deformation of the chimes and the paperboard; and

(1. said thermoplastic material between the plies of paperboard having a greater elasticity in the area underneath the metal chimes than the thermoplastic material between the metal chimes. 

1. In a fibre drum container having a tubular body member and a closure attached to at least one end by deformation of the tubular body member, the improvement comprising: a. several plies of convolutely wound paperboard; and b. a layer of thermoplastic adhering the plies of paperboard to one another, means for permitting deformation of the body member adjacent said one end without rupture of the paperboard, said means including said thermoplastic adjacent the deformed end having a greater elasticity than the remaining thermoplastic.
 2. An article as recited in claim 1 in which said greater elasticity is obtained by: a. increased thickness of the thermoplastic layer adjacent the deformed end as compared to other of said thermoplastic layer.
 3. An article as recited in claim 1 in which: a. the thickness of the layer of thermoplastic is uniform; and b. the thermoplastic adjacent the deformed end has a greater percentage elongation prior to rupture.
 4. A convolute wound fibre drum comprising: a. several plies of convolutely wound container board for forming a tubular member, said plies being adhesively secured one to another by a layer of thermoplastic material; b. a metal chime at each end of said tubular member for securing a closure thereto, said chime being attached to said tubular member by indentation of a portion of said chime and said tubular member; and c. said layer of thermoplastic material being said plies and intermediate the indentations having a maximum thickness of 0.5 mils, and a thickness greater than 0.5 mils at said indentation for providing elasticity to the tubular member to preclude rupture of the fibre thereof.
 5. A container comprising: a. several plies of paperboard convolutely wound into a tubular member and forming an annular upstanding side wall having two open ends; b. a thermoplastic adhering the plies of paperboard one to another; c. metal chimes secured to said open ends for the attachment of end closures to the tubular member, said chimes extending a short distance beyond the ends of the tubular member and overlying a portion of the side walls, said chimes being secured to the tubular member by an annular deformation of the chimes and the paperboard; and d. said thermoplastic material between the plies of paperboard having a greater elasticity in the area underneath the metal chimes than the thermoplastic material between the metal chimes. 